1. Field of the Invention
This invention relates to T-joint fittings of the type which are attachable to a fluid pipe and cut an opening therein.
2. Description of the Prior Art
There are many types of T-joing fittings, which are adapted to be attached to a fluid transporting pipe and make possible the attachment of a bleed-off pipe, without the necessity of emptying the transport pipe.
One such T-joint fitting is shown in U.S. Pat. No. 3,983,897, S.R.V. Gebelius, and comprises a two-part housing adapted to be tightly attached to a transport pipe. The housing encloses an axially displaceable piston, the front edge of which is shaped to cut a hole in the wall of the transport pipe, and to bring the chip removed from the wall to a recess in the housing.
When the transport pipe is made of steel, a considerable force is required to make the piston cut through the wall of the pipe. This force is obtained by the ignition of an explosive charge, or possibly by the stroke of a sledge hammer.
The use of an explosive charge makes it necessary to provide a strong housing, and it is also, otherwise, necessary to consider various safety regulations. A hard stroke may damage a soft-material tube.